Name the toolchain copy of mold ld64.mold in lto-library-default

The test linked mold into a toolchain's bin directory as ld, but mold
acts as the Mach-O linker only under the name ld64.mold, so the copy
ran the ELF linker and failed on -arch. The test checks that the
linker loads the libLTO in lib beside its bin directory, which doesn't
depend on the name.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

tests/macho/lto-library-default.sh

@@ -11,13 +11,15 @@ EOF
 # Without -lto_library, the linker takes the libLTO in lib beside the
 # bin directory it runs from, as ld-prime links its toolchain's. (The
 # system's ld is a shim that can't run from a copy; it finds Xcode's.)
+# The copy keeps the name ld64.mold, under which mold acts as the Mach-O
+# linker.
 ld=$mold
 if is_mold; then
   rm -rf $t/tc
   mkdir -p $t/tc/bin $t/tc/lib
-  ln $mold $t/tc/bin/ld 2> /dev/null || cp $mold $t/tc/bin/ld
+  ln $mold $t/tc/bin/ld64.mold 2> /dev/null || cp $mold $t/tc/bin/ld64.mold
   ln -s $lto_library $t/tc/lib/libLTO.dylib
-  ld=$t/tc/bin/ld
+  ld=$t/tc/bin/ld64.mold
 fi
 $ld -arch $ARCH -platform_version ${PLATFORM_VERSION:-macos 13.0 13.0} -syslibroot $SDK -lSystem $t/a.o -o $t/exe
 $RUN $t/exe | grep -q Hello